xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

bpf, netns: Handle multiple link attachments

Browse Source 
Extend the BPF netns link callbacks to rebuild (grow/shrink) or update the
prog_array at given position when link gets attached/updated/released.

This let's us lift the limit of having just one link attached for the new
attach type introduced by subsequent patch.

No functional changes intended.

Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200717103536.397595-2-jakub@cloudflare.com
This commit is contained in:
Jakub Sitnicki
2020-07-17 12:35:22 +02:00
committed by Alexei Starovoitov
parent bfdfa51702
commit ce3aa9cc51
3 changed files with 139 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

90
kernel/bpf/net_namespace.c
View File

@@ -36,12 +36,50 @@ static void netns_bpf_run_array_detach(struct net *net,
bpf_prog_array_free(run_array);
}
static int link_index(struct net *net, enum netns_bpf_attach_type type,
struct bpf_netns_link *link)
{
struct bpf_netns_link *pos;
int i = 0;
list_for_each_entry(pos, &net->bpf.links[type], node) {
if (pos == link)
return i;
i++;
}
return -ENOENT;
}
static int link_count(struct net *net, enum netns_bpf_attach_type type)
{
struct list_head *pos;
int i = 0;
list_for_each(pos, &net->bpf.links[type])
i++;
return i;
}
static void fill_prog_array(struct net *net, enum netns_bpf_attach_type type,
struct bpf_prog_array *prog_array)
{
struct bpf_netns_link *pos;
unsigned int i = 0;
list_for_each_entry(pos, &net->bpf.links[type], node) {
prog_array->items[i].prog = pos->link.prog;
i++;
}
}
static void bpf_netns_link_release(struct bpf_link *link)
{
struct bpf_netns_link *net_link =
container_of(link, struct bpf_netns_link, link);
enum netns_bpf_attach_type type = net_link->netns_type;
struct bpf_prog_array *old_array, *new_array;
struct net *net;
int cnt, idx;
mutex_lock(&netns_bpf_mutex);
@@ -53,9 +91,27 @@ static void bpf_netns_link_release(struct bpf_link *link)
if (!net)
goto out_unlock;
netns_bpf_run_array_detach(net, type);
/* Remember link position in case of safe delete */
idx = link_index(net, type, net_link);
list_del(&net_link->node);
cnt = link_count(net, type);
if (!cnt) {
netns_bpf_run_array_detach(net, type);
goto out_unlock;
}
old_array = rcu_dereference_protected(net->bpf.run_array[type],
lockdep_is_held(&netns_bpf_mutex));
new_array = bpf_prog_array_alloc(cnt, GFP_KERNEL);
if (!new_array) {
WARN_ON(bpf_prog_array_delete_safe_at(old_array, idx));
goto out_unlock;
}
fill_prog_array(net, type, new_array);
rcu_assign_pointer(net->bpf.run_array[type], new_array);
bpf_prog_array_free(old_array);
out_unlock:
mutex_unlock(&netns_bpf_mutex);
}
@@ -77,7 +133,7 @@ static int bpf_netns_link_update_prog(struct bpf_link *link,
enum netns_bpf_attach_type type = net_link->netns_type;
struct bpf_prog_array *run_array;
struct net *net;
int ret = 0;
int idx, ret;
if (old_prog && old_prog != link->prog)
return -EPERM;
@@ -95,7 +151,10 @@ static int bpf_netns_link_update_prog(struct bpf_link *link,
run_array = rcu_dereference_protected(net->bpf.run_array[type],
lockdep_is_held(&netns_bpf_mutex));
WRITE_ONCE(run_array->items[0].prog, new_prog);
idx = link_index(net, type, net_link);
ret = bpf_prog_array_update_at(run_array, idx, new_prog);
if (ret)
goto out_unlock;
old_prog = xchg(&link->prog, new_prog);
bpf_prog_put(old_prog);
@@ -309,18 +368,28 @@ int netns_bpf_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
return ret;
}
static int netns_bpf_max_progs(enum netns_bpf_attach_type type)
{
switch (type) {
case NETNS_BPF_FLOW_DISSECTOR:
return 1;
default:
return 0;
}
}
static int netns_bpf_link_attach(struct net *net, struct bpf_link *link,
enum netns_bpf_attach_type type)
{
struct bpf_netns_link *net_link =
container_of(link, struct bpf_netns_link, link);
struct bpf_prog_array *run_array;
int err;
int cnt, err;
mutex_lock(&netns_bpf_mutex);
/* Allow attaching only one prog or link for now */
if (!list_empty(&net->bpf.links[type])) {
cnt = link_count(net, type);
if (cnt >= netns_bpf_max_progs(type)) {
err = -E2BIG;
goto out_unlock;
}
@@ -341,16 +410,19 @@ static int netns_bpf_link_attach(struct net *net, struct bpf_link *link,
if (err)
goto out_unlock;
run_array = bpf_prog_array_alloc(1, GFP_KERNEL);
run_array = bpf_prog_array_alloc(cnt + 1, GFP_KERNEL);
if (!run_array) {
err = -ENOMEM;
goto out_unlock;
}
run_array->items[0].prog = link->prog;
rcu_assign_pointer(net->bpf.run_array[type], run_array);
list_add_tail(&net_link->node, &net->bpf.links[type]);
fill_prog_array(net, type, run_array);
run_array = rcu_replace_pointer(net->bpf.run_array[type], run_array,
lockdep_is_held(&netns_bpf_mutex));
bpf_prog_array_free(run_array);
out_unlock:
mutex_unlock(&netns_bpf_mutex);
return err;